Brief description of the catalytic component on a porous metallic oxide support for the gas-phase polymerization of olefins. Application of the catalyst obtained at the polymerization of olefins

摘要

Treatment process making it possible to maintain the morphology of a catalyst component for the gas-phase polymerisation or copolymerisation of ethylene or of ethylene and of at least one alpha olefin containing from 3 to 12 carbon atoms, the said component containing at least titanium, magnesium, chlorine and optionally an electron-donor, the process consisting, after impregnation of a porous metal oxide support with titanium, magnesium and chlorine compounds and optionally with the electron-donor, in involving this catalyst component in the presence of an alkylaluminium-based cocatalyst in a prepolymerisation, at least partially in suspension, of ethylene or of ethylene and of an alpha-olefin characterised in that the prepolymerisation is conducted, in the presence of a cocatalyst consisting of an alkylaluminium complexed with an electron-donor to a degree of prepolymerisation appropriate to the gas-phase polymerisation process in which the resulting active prepolymer will subsequently be used.